It has been known that a deviation may be produced between a sensible speed for a driver of a vehicle during traveling of the vehicle and an actual traveling speed of the vehicle. For example, a deviation between the traveling speed and the sensible speed may be easily produced when a traveling road of the vehicle switches to an ordinary road from a highway allowing a higher legal speed limit than that of the ordinary road.
In order to secure safe traveling of the subject vehicle even under such a deviation, a technology disclosed in Patent Literature 1 forcedly reduces a traveling speed of the subject vehicle to a speed limit or lower through control of driving force of the subject vehicle to assist safe driving.